Expansible pulley



Se t. 23, 1952 J. MITCHELL EXPANSIBLE PULLEY 3 Sheets-Sheet 2 Filed April 24, 1950 Inventor: W

2a Attorne MMM 3 Sheets-Sheet 3 Filed April 24, 1950 Patented Sept. 23, 1952 1 EXPANSIBLE PULLEY' James Mitchell Marfleet, Hull, 7 to J. H. Fenn'er & Company England, assignor Limited, Marfleet,

Hull, Englandya'British company Application April 24,1950, Serial No. 157,809

Great Britain April 25, 1 949- This invention is concerned with'variable speed belt transmission mechanism of the type in which pulleys are used having conical flanges, which flanges can be moved apart against spring action or allowed to come nearer together, in order to varythe efiective diameter of the pulley for transmission purposes. The flanges are pressed toward one another by powerful springs, and the speed variation between driving and driven shafts is obtained by moving the axis of one pulley'towards or away from that of. the other, or by the 'use of a jockey pulley altering the run of the belt One convenient arrangement is that in which the expanding pulley is on the shaft of an electric motor mounted to slide on a base and to be adjusted by a screw and handwheel. In'

this case, if the motor carrying the expansible pulley is moved further away from the driven shaft the pull of the belt forces apart the flanges of the pulley on the driving shaft thus reducing the efiective diameter of the driving pulley and so reducing the speed ofpower transmission. Adjusting the driving motor nearer to the driven shaft gives the reverse effectallowing the flanges of the pulley to move together and making the pulley effectively one of larger diameter so as,

to increase the driving speed. v The driving belt is either V-shape in transverse cross section or hasits sides-wedge-shaped so as to co-operate efiectively with the conical flanges of the pulley. The expanding pulleycan be either on the driving or on the driven shaft, and its use on the driving shaft has only been mentioned as being generallythe most convenient arrangement. The driven pulley may be a plain or grooved may be itself adjustable in diameter, if required. As-a strong spring must be used for pressing the flanges of the double cone pulleytogether, I the spring has generally had to be a long one in order thatit may sustain the required side pressure, particularly when the flanges of the pulley 1 are closed together and when the spring is therefore .most relaxed. This has necessitated the use of abnormally long springs with longbosses or sleeves which tend to make the variable speed.

-' unit large and cumbersome. If separate springs are-used, one forieach flange, careful adjust- .ment of each spring is necessary to equalize loading so that the beltsmay remain centrally disposed in relation toits line of travel as the pulley is expanded and contracted. The springs may need readjusting after beingin usefora time in order that they may be equallyloaded while the belt, maintains its proper line'of travel throughout therange'of adjustment.-

- 4 Claims. (01. m-zs i'z) V Q It is the object of the present inventionto provide a form of expanding belt pulley with automatic spring control which will be easyto set initially or to adjust when required so'as'to maintain the propenrelative position-of the flanges of the pulley under all conditions. The

expanding pulley may be I a single pulley with two opposed flanges or a multiple pulley with'two or'more pairs of flanges.

The-invention is illustrated by way of example in the accompanying drawings wherein Figures 1, 2, 3 and 4 are longitudinal sectional views "throughshafts and pulleys showing'alternative pulley of fixed diameterzor waysin'which the invention can be applied in practice. Figure 5 is an end view of Figure 1.- I

Referringfirstto Figure 1, a and b are the conical faces of a pulley,'the hub portion s' 'of which flt slidably one on another, and are supported by sleeve 0 upon shaft d, which latter may be, for exampla the spindle of a motor. Sliding keys'e transmit the torque between the hub-portions of cones a and b, and sliding keys f transmit the torque between the hub of cone a and sleeve 0, this-latter being keyed or otherwiseflxed on the spindle d. The V-shaped belt is marked s andis shown at its outermost position when-the cones a and b are in their position of nearest approach to one another. A collar 0 fixed in position by a set screw '0 limits the outward travel of cone 'a on sleeve c.- j

The'cones a and b are drawn toward one another by springs g and h, one outside the other, thespring g embracing the hub portion of comb, and beingseparated from the other spring-h by the cylindrical portion of the equalizer k. "This equalizer has one end turned inwardly as at i to form an abutment for one end of spring 9,

while the other end of this spring bears against the shoulder of a member I formed as a nut for adjustment on the threaded end of the hub porbend to form on the one hand an abutment orfshoulder for the right hand end of spring h to bear against, and-on the other hand to receive screws n by which an end plate or cover 0 can be attached. The springs g and h are enclosed in a telescoping casing consisting of the parts 13 and q, of which part 10- may be integral with the equalizer k, while part q hasits left hand end inwardly turned to act as an abutment. or

shoulder for the left hand end of spring h where it exerts its pressure on cone b.

The cover plate 0 screws upon the threaded. end. r .of the sleeve 0 and is locked in its position of adjustment by grub screws 15 engaging partly in holes in the cover plate and partly in grooves in the threaded end 1'. When the cover plate is so applied, it anchors the equalizer is with reference to sleeve 0 so as to insure that the cones a and 12 move equally towards or away from a median plane between them ras' the. pulley expands and; contracts.

In setting up this pulley, the cover plate 0 is left off, while the springs g and h are assembled is between them, and the telewith the equalizer I scoping casing 72, 0 around them. T-he springs are pre-loaded by screwingupthe nutlon-the end of the hub portion of cone a, thus-applyin pressure to spring 9 and through the equalizer k .15 ,cones in Figure 3.

to spring h and the cone b. At this stage the springs or and h are actin in *seriesran'drzmust therefore be equally loaded. The springs are equally rated for expansion and contraction 111 -7...

der load. The cover plate 0 is now applied and screwed. on ,the threaded. end 1' .of. sleeve. .c .until it-just contactswith the end of lthesequalizerrk. T .The grub. screws. t are then .insertedsto. lock, .the covertplateiagainst. rotatiom and screws fin-bare ,-i-nserted..to-..attach the cover... plate 0 t0 the; ring ..min .the ehdQof; :theQequalizer ,k. .The. parts are .inowdocked ,in ,their position of, adj ustment, and ..should. continueto ,permit lequalfmovements of the cones a and b with respect to amedian plane ..,.;between them, as the pulleys are adjusted-toward or. away. from oneahetheryalthough now the .l .;spring .hr acts. directly: betweenpover. plate 0 and .tsleevegcpn the. one handand the back of cone b on .the ,other hand, andspring: 9 acts directly. .be-

tween sleeve c and the hub of coma. If the-parts .=,.a re.-separated at anytime, for: ie-etensioningthe asprings by nut l for example, or. for replacing-Jone "or-lboth oftl1er sp1:i ngs -g and h,-the same procedure should be followed ..;-to insure..equa l :loading on-the twospringsthrough the equalizerk. The cones-o :and; b with theira-sliding hub; portions, ghaive been eldescribed as. working ;ona sleeve 0 .-whieh is. itself. fixed 'ona shaft. or-spindle d, be- .-;c,ause it is convenient to make the-expandingpulqleywith its-sleeve casaunitfor mounting 'on any shaft. Theconesn-aiand b couldslide directly won.shaftdhowever if; preferred in any. case.

Figure 2..sho,ws a-modified :constructionin @Wh-igh; provision is made-for internal lubrication.

The parts which arethe, samev as in Figure; 11-are lettered;- to correspond with that :flg-ure. The gprincipal diiference is that the threadedend'rrof -;sleeve 0; isomitted, and instead of this a--tubular vstemrt is fitted to the endof-sleeve c. This stem .-=.;carries a collar -7 against 'whichcoyeryplate 0 :isilocated-by nuts 11, while a lubrication nippleu yon the-end of tubular stem r enables lubricant 111053136: introduced, which passes; by-isuitable intergual .oil ducts; to; the working faces. of. the: hubstof .-cones wand b and thesleeve c.

Figure 3, ShGWS hOVL a:multip1e .beltpulieyucan ;be.;constuucted on the 553.1116 principles; asthe sin- ;gle ionen' -.In "this-2.56 sore sho wn--two left-hand scones.a:and: a?,;andztwoirightehandrcones bf; and 11b? .sand .1' two i Iv -.b elts' sf :and i51 theicoixesr being shown :se'para-tedrto. theirmiaximum: extent ;to .tgive pulleys :of :Lhe smallest; effective diameters. 1 ,The springs .91 and h-,E\the equalizer .k, and: their -,:method of; mounting and adjustment, 'are 2 the .-.same; as infigure. 1 andshoulckreduirenoifurther des,cription. :The. cones d and-a?;have:;their hubs -..a-*' and a abutting-1 against apne, another,;:and

keyed to the sleevep;slidingdreys'f; the-two hubs ,being; locked together by;-longeb.01ts a? extending ithrough hub airintoahuhsah :Shnilarly,.1thej;hub of. ,cone' b, has extensions passing through slots in cone a and abutting against the hub b of cone b these two hubs bein locked together by a long bolt b The hubs b and b are keyed to hubs a and a by sliding keys e. Under the 5 equalized pressures of springs g and h, the cones -..a' and. bmoveaapart-orsnearer: together, simul- ..-taneously .with the cones-fa and 11 as .the driving and driven shafts are moved further apart or qmearer together for varying the transmission ratio of the power drive through belts s and 8. "Gi -course, three or more pairs of cones for drivringthrough three or more belts can be intercon- 1 p :1- nected-for simultaneous operation on the same "1prin'cip1enas is'gillustrated for the two pairs of .";The'cover'plate o is not an essential feature "of the invention, and the equalizer is can be left free .to: transmit the pressure from one spring to the other. For example, Figure 4 shows an .arrangement,like thatofFigureJ .exceptthat thepartsn, 0, r andtare omitted, and the equal simultaneous movements. of cones a .and t b towards and away. fromnar median plane between ...them. are .insured. by introducing a rocker. 20.2.01;- ingas a link between-them. The hub-z-portion a of: the cone-a has aslot in itthrough. which the ...rocker w projects. Thisrocker is pivoted-ate in the. end. portion: ofcthe :sleeve member re and has its Tends :curved and provided 'with plastic treads-v of rubber or. the like,-by which these ends bearrespectively onthe inner-surface-of hub portion a and the inner-surface of hub portion-b -,-This-device is only shownes one convenientform of. linkage between the. hubsof cones ag andb, 35. .-and;:any -;equivalent linkage or balancing: gearingserving ther same purposeican bea used; sucha-for -example ias a-soft-tireddisc ora.- gear wheel .or t-toothed seg-ments engaging with 5 gear teeth rin the hubs a and b respectively.

.-It-.-.will;be-'realisedr that, .in' :each of-,the constructions described, the two springs and h .se- -oure-. the advantagesbf .a spring. of double their lengthiin so f an: as equal-resilience, and'low rating spore-unitof compressioniareconcerned;while the aequalizer nsreehanismwhen: used-as.:described.-in-

sures that the two springs.-. arewalwayscequally loaded; andthat the .run; of :the belt ismaintained whenever .thereifective pulley 'diameteryis varied ibyrelative displacement betweenthedriving and n-driven shafts.

, i .I ':claim: V j v I I. Expansible -pulleyiforzuse ;in-.variable. speed transmission of.:nower:.comprising:a pairgofcconical :ilanges; r'having hub. portions :adapted: :to -sli.de';one;upon:the;other,va pair-ofrhelical springs .zacting-in :seriessand equally :rated for: expansion and; contraction under; load, one ;of tsaidgsprings .:being;disposed :aroundithe other; an equalizer :cylinder .idisposed .1.-between-..said springs, said -aequalizer. cylinderchaving. .one. :of .its .EIldS 111- zrwardlyjnirected rand lithe :otherzoutwardly: 1di- -rect'ed,.: and 'a; collanad-justablymaunted .on:the ;hub: portiomof one. of.;said conical flangesrand adapted :toztakezthesthrust. of :the; inner ..one:;of .:said helical 'springsbetween 1- the'ginwardly. di- ..:r.ected send; of: said .equalizenzand :the .hubzpor- ".tiongof zone :of :said ..;conical :flanges, .while I the --outer one-{of '-.saidiheliealz:springs isso disposed "as to exert:its thrustlbetween the other one of -.sai'd; conical flanges and the outwardly directed send of:said equalizer.

Expansiblepulley for use 1 in variable :speed transmission 'of power= comprising --a=pairof conical flanges having hub portionsadaptedto slide one upon-the otherapairof helicaksprings l-ar adjustably mounted on the hub portion of its ends inwardly directed and the other outwardly directed, a col-r one of said conical flanges and adapted to takeff the thrust of the inner one of said helical springs between the inwardly directed izer and the hub portion of one of said coni: cal flanges, while the outer one of said helical springs is so disposed as to exert itsthrust between the other oneof said conical flanges and the outwardly directed end of said'equal; izer, in combination with a sleeve member slid.- ably mounted within the hub portions oi said conical flanges, means for keying together such sleeve member and said hub portions while permitting relative axial movements between them, and an end cover with means for adjustably fixing it at one end ofsaid sleeve member,and attaching it to said equalizer after said helical springs have been subjected to compression:

3. Expansible pulley for use in variable speed transmission of power comprising a plurality of pairs of conical flanges disposed in right and left opposed relation, and having hub portions adapted to slide axially upon and within one another, means connecting together the hub portions of said right hand flanges and said left hand flanges respectively, for simultaneous axial movements one upon the other, means for keying together said relatively movable hub-portions in pairs, w e permitting of their axial movements, 9. pair of helical springs one disposed around the other, an equalizer cylinder disposed between said springs, said equalizer cylinder having one of its ends inwardly directed and the other outwardly directed, a collar .adjustably mounted upon the hub portion of one of said conical flanges and adapted to take the thrust of one of said helical springs between the inwardly directed end of said equalizer and the hub portion of the conical flange on which said collar is mounted, while the other said helical springs transmits its thrust between the outwardly directed'end of said equalizer and an opposing conical flange member oisaid expansible pulley, in combination with a sleeve end of said equa'il member slidably mounted within the im'ir hub portions of said conical flanges, means for keying said sleeve member to said inner hub portions of said conical flanges, and an end cover with means for adjustably fixing it at one end of said sleeve member and attaching it to said equalizer after said helical springs have been subjected to compression.

4. Expansible pulley for use in variable speed transmission of power comprising a pair of conical flanges with hub portions adapted to slide one upon the other, means for keying said hub portions together for simultaneous rotation, a pair of helical springs one surrounding the other, an equalizer betweensaid springs having one end inwardly directed and "the other end outwardly directed and adapted to form abutments for one end of each of said springs, a collar adjustably mounted on the hub portion of one of said conical flanges and adapted to apply compression stresses directly to one of said springs and indirectly to the other of said springs through said equalizer while the inner end of the outer of said springs transmits a thrust upon the back of one of said conical flanges, incombination with an axial support for said hub portions and means for .aflixing said equalizer to said axial support when said springs are under compression.

JAMES MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

